One might think Summaron 28mm lens is not suitable for building interior photos as the wide open aperture value starts from F/5.6 however, with Leica M10, you can shoot it with acceptable noise level in handheld. Also modern Summaron lens is very sharp like any other Leica lenses, so it’s great for exterior of a building photos.
As far as wide angle distortion goes, considering Summaron lens size is extremely small, I hardly see any disturbing distortion in every photos. It seems like Leica Q has more distortion than Summaron 28mm on Leica M10
Usually with wide angle lens such as 28mm or even more wider lens like 24mm, you begin to see noticeable distortion. I am not a big fan of wide angle distortion. So maybe 28mm is the widest angle I could enjoy. With this said, Summaron seems a perfect match for me. Very small but sharp yet almost no distortion.
In combination with Leica M10 (which is great for low light photography among Leica M bodies) , Summaron 28mm is the best kit for building both interior and exterior photos.